Plant Biology

Roots Stems and Leaves

Here are a number of sites on roots, stems and leaves. Check out the site for general to pretty specific information.
roots and stem atanomy
leaf anatonomy
plants and their structure
plants tissues
plant cells and tissue 1
plant cells and tissue 2

Check out these modifications -

at least one definition will surprise you.
modified roots stems
Growing rhizomes
Grass growing

Leaf modification video
Modified leaves
Wayne's word vegetative terminology